1. Field of the Invention
The present invention relates to a magnetic tape unit for performing read/write of data on a magnetic tape.
2. Description of the Related Art
In recent years, a magnetic tape unit using a magnetic tape as a storage medium has been developed and put into practical use as an external storage device for a computer. In a read/write operation of the magnetic tape unit, the magnetic tape is traveled in contact with the magnetic head. In waiting for a read/write process, the magnetic tape is kept in contact with the magnetic head. Accordingly, if such a waiting condition continues for a long time, there is a possibility that the magnetic tape may adhere to the magnetic head; so, the measures for solving this problem have been desired. In a particular case that an air escaping groove is formed on a magnetic tape contact surface of the magnetic head, so as to make a good contact between the magnetic tape and the magnetic head, there is a possibility that the shape of this air escaping groove may be transferred to the magnetic tape to make the surface of the magnetic tape uneven, causing an error in the read/write operation.
One of the conventional methods for preventing the adhesion of the magnetic tape to the magnetic head or preventing the transfer of the groove shape to the magnetic tape is to provide a gap at a central portion of the magnetic head and blow air against the magnetic tape from this gap with an air pump, thereby avoiding the contact between the magnetic tape and the magnetic head. Another conventional method is to perform a reciprocating motion of the magnetic tape by a small distance during a rest period where the read/write operation of the magnetic head is not performed (Japanese Patent Publication No. 57-8533).
In the former method, the air pump, which is expensive and large, is required to avoid the contact between the magnetic tape and the magnetic head, causing a difficulty of reduction in size and cost of the magnetic tape unit. In the latter method, the short-distance reciprocating motion of the magnetic tape is performed usually with a predetermined period, which is set to a constant value irrespective of temperatures in the magnetic tape unit. Accordingly, the following disadvantage occurs. In general, the higher the temperature, the more the adhesion of the magnetic tape to the magnetic head tends to occur. However, if the period of the reciprocating motion is set to a unduly short period in spite of low temperatures, the magnetic tape may be damaged by the reciprocating motion, whereas if the period is set to a long period in spite of high temperatures, the adhesion of the magnetic tape to the magnetic head cannot be prevented.
It is therefore an object of the present invention to provide a magnetic tape unit which can be reduced in size and cost and can well prevent the adhesion of the magnetic tape to the magnetic head irrespective of temperatures in the tape unit.
In accordance with a first aspect of the present invention, there is provided a magnetic tape unit comprising a magnetic head for reading and writing data from and onto a magnetic tape; driving means for traveling the magnetic tape kept in contact with the magnetic head during a read/write operation of the magnetic head; means for performing a reciprocating motion of the magnetic tape by a small distance with a predetermined period during a rest period where the read/write operation of the magnetic head is not performed; a temperature sensor for detecting a temperature in the vicinity of the magnetic head; and control means for changing the predetermined period of the reciprocating motion according to the temperature detected by the temperature sensor.
In accordance with a second aspect of the present invention, there is provided a magnetic tape unit comprising a magnetic head for reading and writing data from and onto a magnetic tape; driving means for traveling the magnetic tape kept in contact with the magnetic head during a read/write operation of the magnetic head; and control means for changing a tension of the magnetic tape during a rest period where the read/write operation of the magnetic head is not performed.
Preferably, the magnetic tape unit according to the second aspect of the present invention further comprises a temperature sensor for detecting a temperature in the vicinity of the magnetic head, wherein the control means changes the tension according to the temperature detected by the temperature sensor.
In accordance with a third aspect of the present invention, there is provided a magnetic tape unit comprising a magnetic head for reading and writing data from and onto a magnetic tape; driving means for traveling the magnetic tape kept in contact with the magnetic head during a read/write operation of the magnetic head; a temperature sensor for detecting a temperature in the vicinity of the magnetic head; and means for canceling the contact between the magnetic tape and the magnetic head when the temperature detected by the temperature sensor is higher than or equal to a reference temperature.
According to any one of the first to third aspects of the present invention, the air pump for avoiding the contact between the magnetic tape and the magnetic head is not required, thereby allowing a reduction in size and cost of the tape unit. Furthermore, since the temperature sensor for detecting a temperature in the vicinity of the magnetic head is provided, and various controls are performed according to the temperature detected by the temperature sensor, the adhesion of the magnetic tape to the magnetic head can be well prevented irrespective of temperatures in the tape unit.
As mentioned previously, in the case where the air escaping groove is formed on the magnetic tape contact surface of the magnetic head to make a good contact between the magnetic tape and the magnetic head, the shape of this groove may be transferred to the magnetic tape to make the surface of the magnetic tape uneven, causing an error in the read/write operation. This problem can be prevented by the present invention.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.